In mechanical constructions, the movements of parts can broadly be classified into two categories: translation and rotation. In this application we concentrate on the rotation of an object. In many optical applications the redirection of light is a desired condition, such as in scanners, optical switches, in laser printers, bar code readers, projection TV, laser radar, imaging applications, and the like. Mirrors such as those in galvanometric mirror systems that can be rotated are typically fabricated using classical mechanical workshop techniques.
In certain applications the scanning speed is of importance, for instance in the case of certain medical laser imaging techniques, where a patient is subjected to a laser beam for imaging purpose, but where this laserbeam would cause harm to the patient if the dwelling time would be to long. In particular, in laser ophthalmology, when a laserbeam is used to scan over the retina, such a high speed scanner has advantages over a low speed scanner, where the retina is subjected to a slower moving laser spot, which can cause discomfort or harm to a patient.
Another field of application is the field of laser radar, wherein a laser beam is used as a radar beam. For the detection of objects that move at high speed, such as missiles, it is desirable to have the shortest possible time between two successive intersections of the interrogating beam and the moving object. Therefore here a high speed laserscanner is also useful in such an application.
Such techniques cannot easily be implemented into a format in which a rotating mirror construction is fabricated in a set of fabrication methods commonly referred to a MEMS techniques. MEMS is an acronym standing for Micro Electro Mechanical Systems. In MEMS technology the techniques of integrated circuit technologies are applied for the fabrication of mechanical systems.
The current invention relates to the field of fabricating a rotatable mirror contruction using MEMS techniques. Within the field of rotatable MEMS mirrors systems a unique position is taken by piezoelectrically actuated mirror systems such as the so-called double “J” system by Smits et al. See Reference [1]
Workings further with the possible applications of piezoelectric benders, we discovered new constructions, which were the subject of a previous application. See Reference [2].
Continuing these detailed investigations we discovered another useful device that is the subject of this current application.
The difference between the device in this current application and the device that is described in U.S. Pat. No. 7,005,781, is that the current devices uses very wide bending elements, much wider than would be allowed under the common assumption that states that the behavior of cantilever beams can be calculated using the Euler-Bernoulli equation if they are “long and slender”.
Therefore the behavior of the device in the current application cannot be calculated analytically, but only by numerical methods, such as the Finite Elements Analysis method. As it was possible to calculate the behavior of the previous device by analytical means, whereas it is impossible to do so with the current device, because the boundary conditions do not allow us to do this, the current device is not identical to prior art, and could not be foreseen by anyone sufficiently well acquainted with the prior art.